Corolla XRS- ecomodding

[DieselHybrid]

Hi,

I am the owner of a '06 Corolla XRS. EcoMods to date:

ScanGauge
Light Motegi Traklite rims
205-55-16 (vs. stock 195-55-16) results in 1.77% taller gearing
tires inflated to 44psi
Mobil 1 synthetic
Lowered 1.2" from stock (XRS is already 1" lower than regular Corollas)
antenna replaced with "shark fin"
Vortekz VGs

My best mpg tank to date is 36.3 mpg with a lifetime (40% city / 60% hwy) average of 31.9mpg. (XRS new rating is 22/31mpg- old 26/34mpg) I've hit a wall; as this is the best I can do.

Admittedly, the Achilles heel of the XRS is its "sport" gearing. Even with my taller tires my engine revs at 2662 rpm at 60mph and 3106 rpm at 70mph. Way too high!

I would desperately like to swap out my 6th gear ratio from a 0.725 to 0.659 or so. This would reduce my rpms to 2420 and 2823 rpm at 60 and 70mph respectively.

As far as driving style is concerned, I shift early without lugging, and fight the temptation to use the 2ZZ engine's "lift" (@ 6,200rpm the Yamaha-designed engine switches cam profiles for more power).

Anyone know where I can find a 6th gear swap for the Toyota Corolla XRS?
Any other ideas as to how to improve fuel economy with my car?
Thanks in advance!

[PaleMelanesian]

Pulse and Glide, baby! Use the engine to it's full capacity in a burst, then glide and milk it for all it's worth.

My Civic runs 2750 at 60mph.

[DieselHybrid]

WOW: +66mpg and 2750 rpm at 60mph... Hmmmm

O.K.- help me out. I thought I knew how to P&G- but I can't seem to break past 36mpg. I glide in neutral when able and turn off the engine at stoplights.

"Using the engine at it's full capacity in a burst..."

My XRS happily revs to 8,200 rpm. I generally don't go there as my scan gauge shows mpg drops precipitously when in "lift" (anything above 6,200rpm).

What do you cruise at on the hwy? I maintain 70mph- usually no higher.

Help me break 40mpg! What is the best P&G technique?
Thanks in advance!

[PaleMelanesian]

Ok, first thing, don't go anywhere near that 8200 rpm. I haven't touched 3,000 in months.
Read this article for background: Autospeed - BSFC

Do you have a lot of highway driving? That's going to be tough with the gearing you have. Slowing down it the best option. I like to P&G in a 45-60 mph range when traffic allows.

P&G - the pulse should be in the 1500-2200 rpm range, at near but not quite full throttle. You have a powerful engine, so it'll pick up speed in a short time. Try to time the p&g cycles to maximize the glide, even to the point of pulsing uphill for a long downhill glide.

EM's own 100+ hypermiling tips is a great resource. Also, CleanMPG's review of the Corolla XRS.

Do you have the built-in economy gauge? If not, I suggest getting a Scangauge or mpGuino for feedback.

[DieselHybrid]

Great article! If they can manage 60mpg with the 2009 2.4 liter XRS, then surely I should be able to do the same with my 2006 1.8 liter XRS.

I have a scan gauge. So for hypermiling purposes, I should be monitoring TPS(?) and Load? What is TPS?

The article says to limit TPS to no more than 33 and Load to 94%. On the highway they recommend TPS of 29 and Load of 70-85%.

Granted, I have a different engine than the article, but I'll give this a try.

[PaleMelanesian]

Oh, I didn't realize yours was the earlier model. The numbers are probably similar, though.

I like to watch Load. Above 95% or so, it goes into Open Loop and enrichment - dumps extra fuel in. Avoid that. TPS is simply throttle position - your right foot. I use ~75% load for my pulses. For steady state, try backing off the throttle a notch when you're at speed. You can likely let it up a notch and still maintain speed, with a couple mpg gain.

[DieselHybrid]

O.K.-

I completed a round-trip 180 mile drive today- mostly highway and backroads. I did my best P&G while monitoring TPS and Load closely. Hwy speeds kept below 75mph.

At the end of the day my SG said I averaged 42mpg- yay!

However, when I went to fill up at the pump I only got a measly 32.8mpg (corrected miles actually driven divided by fuel purchased). Granted, I burned less than half a tank to include approximately 20 miles of non-P&G city driving before this test run.

Is something wrong with my SG? Every fillup I re-calibrate. For example, the SG said I burned 5.2 gallons of fuel- when in reality I filled up with 6.02 gallons- a 15.8% difference. I re-calibrate my SG every time- as it says I burn less fuel than I actually fill up with.

My fuel source is Sam's Club- and they are quite reputable.

HELP!
Thanks in advance.

[trikkonceptz]

Na, the scanguage is funny like that, I am consrtantly adjusting mine after each fill up. So use is as a general guide.

Now as much as this reality check hurts, you will not see appreciable gains in FE until to slow down below 65mph. 55mph being ideal.

Otherwise be happy with what your car gives you, because if you are not willing to change your driving you will not see the benefits from it.

Yeah its harsh but true, and no you will not be shot for driving slower on the highway, I traverse 120 miles a day on 1-95 in Florida during congested traffic hours and have yet to get honked at or high beamed in the 7 months that I have slowed down to 55mph in the 65-70mph posted speed limit zones I drive. It's in your head ... LOL

[fanamingo]

I recommend against recalibrating the ScanGauge every tank. It doesn't "learn"; it just uses the most recent offset you entered. The SG may be off more for some types of driving than for others. Instead, set it to 0% offset. For your next ~5 full tanks at 0% offset, record gallons at the pump, odometer reading, SG gallons used, and SG miles driven. After 5 tanks, add up the numbers in each category. Figure out if you need to adjust the SG miles driven offset. Then adjust the SG offset for gallons used based on the amount you actually filled up with. This approach should average out inconsistencies and give you better accuracy on average.

[DieselHybrid]

Thanks for the SG gouge! I'll also try to reduce my hwy cruising speeds by 5mph- I'll be sure to post the results.

I've been examining my car for additional clues as to why my FE sucks.

1. My tire press reading dropped to 40.5 psi- on account of the lower ambient temperature. I'll inflate them back up to 44psi.

2. Time for an oil change? Checking my log, the last oil change was back in February- <5,000 miles ago. (2nd car- doesn't get driven as much) I use fully synthetic- which should be good for 7,500 miles. But, I'll change it.

3. DRL's. I've read here that DRL's cause the alternator to run continuously- thus burning more fuel. Can DRL's be disabled- and has anyone expereinced a gain in FE on account of this mod? Is the FE gain big enough to be worth it?

4. Under car aero. I am investigating fabricating coroplast (or similar) panels to reduce the turbulence under my vehicle. Anyone out there have experience doing this on a Corolla? (or Toyota Sienna?)

5. Underhood temps? Now that it is colder, I am considering fabricating grill blocks. Any help- again Corolla, or Sienna?

6. The tranny fluid? I understand that Toyota uses Synthetic tranny fluid from the factory. (I know this is true in family vehicle, auto tranny Toyota Sienna- so I assume it is true in my XRS' 6-speed manual)

Thanks in advance for you helpful inputs and suggestions.